The invention relates to a device for pneumatically feeding fiber flocks, e.g. cotton, synthetic fibers etc. to the next device, e.g. processing machine such as a card etc., in that, via a conduit, the fiber material is supplied to a feeding chute.
The pipe lines customarily used for pneumatically feeding fiber material have a round cross section, in other words, they are designed as tubular cylindrical parts having a circular cross section. For feeding a chute, serving for instance as a supply to a processing machine, the portion conducting the air-fiber-stock flow is box-shaped just like the chute by itself which mostly has an oblong rectangular cross section. The feed line by itself for pneumatically supplying the fiber material being a round channel, it is necessary to provide a transitory pipe member in which the round cross section gradually changes into an upright rectangular cross section. The feed subsection on the chute is a rectangular box corresponding to the horizontal rectangular cross section of the chute. The width of the feeding member is equal to that of the chute.
A box-shaped feed portion on the box-type feeding chute is unfavorable in many respects. Apart from the fact that during the flow through the transitory member from a circular cross section at the beginning to a rectangular cross section at the end, flow losses are caused by friction and so-called dead corners may be formed, a box-shaped feed member on the chute does not ensure a uniform distribution of the fiber flocks over the width of the chute with a resultant uniform formation of a fiber column. Therefore, the dropping of fiber flocks in the rectangular chute is relatively irregular and the fiber flock distribution over the width of the feeding chute is non-uniform. Fibers are accumulated at the bottom portion of the chute. A correction of the fiber column over the width of the chute as far as to the opening means etc. is rather accidental and mostly unachievable. This is particularly true if a plurality of chutes are fed by one and the same feed conduit. The feed member adapted to the cross section of the chute is relatively high so that a diffuse setting of the fibers is favored. Due to its height, the tubular feed conduit is relatively far away from the beginning of the chute thus excluding a certain air balance within the feed member. In addition, the input and exit of the tubular feed conduit are often directly provided to the feed member, thus resulting in sudden cross sectional changes which may bring about undesired turbulations so that the feeding of the fiber flow is no longer under control.